Not necessarily Epping specifically, I'm going to Swinley this weekend and attending @t_w's Surrey Hills ride on the 19th, although Epping's where I'll spend the majority of my weekends as it's near me.
Last time I was in the SH, I was on Rocket Ron 2.2" which on reflection was a brave choice as it doesn't really meet the 'grippy' criteria. Least it was dry :)
For epping specifically? Something narrowish that cuts through the mud might be good, maybe nobby nic / racing ralph in 2" or less.